1. Field of the Invention
This invention relates generally to engine control systems for internal combustion engines, and in particular to a method and system for cooling electronic components thereof.
2. Background Art
Today's automotive internal combustion engines are now almost universally computerized distributorless or direct ignition, fuel injection engines. Such an engine includes a computerized control system, commonly known as an engine control unit (ECU), which controls fuel injection, ignition, and typically other various engine and automotive systems as preprogrammed functions of numerous signals received from various sensors. One or more driver circuits amplify and condition the controls signals to be suitable for use with the fuel injection and ignition components.
Fuel injection systems use one or more fuel injectors, which are electromechanical devices that meter and atomize fuel. In each injector, application of an electrical current to a coil lifts a spring-loaded needle within a pintle valve off its seat, thereby allowing fuel under pressure to be sprayed through an injector nozzle to form a cone pattern of atomized fuel.
Fuel injection systems may be classified as single point, multi-point, or direct injection. In multi-point configurations, there are generally as many fuel injectors as there are cylinders, and the fuel injectors dispense fuel into the induction manifold near their associated intake valves. A fuel rail (a manifold so called because of its rail-like shape) is typically used to deliver fuel to individual fuel injectors. The fuel rail has a number of seats formed therein. Each injector is received into and seals against its seat. The fuel rail has an inlet port, and possibly a filter, a cross-over port, an attached fuel pressure regulator and/or a fuel pressure sender.
Distributorless or direct ignition systems use a crankshaft sensor that provides a trigger signal to the ECU, which triggers the correct channel and timing of the ignition. An individual coil per cylinder, coil packs with multiple secondary terminals, or a common coil configuration may used. The coil(s) are selectively switched to an energy source through a driver that is triggered by the ECU. These drivers are sometimes incorporated into the ECU, and other times in the coils themselves.
To minimize cost, original equipment manufacturers (OEM) of automobile collocate the ECU microprocessor and driver circuits in a single assembly, often on a single printed circuit board. The ECU is typically mounted at a distance from the engine—under the dashboard in the cabin, on the firewall, or elsewhere in the engine compartment, for example. The ECU is typically encapsulated by an epoxy potting compound within a finned metal housing, which radiates heat generated by the electronic components into the atmosphere. The numerous control outputs and sensor inputs are routed within a large vehicle harness assembly.
As ECUs become more advanced, monitoring more parameters and controlling more systems with greater sophistication and speed, processor computational demands increase. This trend, coupled with continued miniaturization of semiconductor technology, results in more localized heat being generated by ECUs and concomitant shorter mean time between failures for ECUs.
3. Identification of Objects of the Invention
A primary object of the invention is to provide an engine control unit having superior cooling for increased reliability.
Another object of the invention is to provide a method of liquid cooling for electronic components using the fuel system as a heat sink.
Another object of the invention is to provide an ECU for engine control with superior aesthetic appeal.